A SUBSTITUTE  FOR  TANNIN 


By 


ABE  MORRIS  SAX 


THESIS 

FOR  THE 


DEGREE  OF  BACHELOR  OF  SCIENCE 

IN 

CHEMICAL  ENGINEERING 


COLLEGE  OF  LIBERAL  ARTS  AND  SCIENCES 

UNIVERSITY  OF  ILLINOIS 


1921 


/ 92  / 
Sa.37 


- 

UNIVERSITY  OF  ILLINOIS 

July_8 I92l__ 

THIS  IS  TO  CERTIFY  THAT  THE  THESIS  PREPARED  UNDER  MY  SUPERVISION  BY 

Ab  e_  Morr  is  _ Sax 

ENTITLED _A_  _Su.bsiii.ut_e  _ Hqz.  - Yannin 


IS  APPROVED  BY  ME  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR  THE 

degree  of Bachel_pr__of  


Approved  : 


HEAD  OF  DEPARTMENT  OF 


Ciiejulutry. 


Digitized  by  the  Internet  Archive 
in  2016 


https://archive.org/details/substitutefortanOOsaxa 


Acknowledgement . 

The  writer  wishes  to  acknowledge 
indebtedness  to  Dr.  Roger  Adams  for 
his  interest  and  valuable  advice  to- 
wards this  work. 


1. 


Table  of  Contents. 

pages 

I.  Introduction  2 

II.  Historical  

III.  Theoretical  5 

IV.  Experimental  7 

1.  Cymene  Sulfonic  Acid  7 

Preparation,  tests,  and  tanning  action. 

2.  Condensation  of  Cymene  Sulfonic  Acid  with 

Formaldehyde  8 

Preparation,  tests,  and  tanning  action. 

3.  Other  substances  10 

V.  Summary  and  Conclusion  10 

VI.  Bibliography  12 


, >: 


2. 

Introduction. 

Within  the  past  decade  certain  definite  advances  have  been 
made  in  th6  manufacture  of  leather.  One  of  these  has  been  the  use 
of  synthetic  tanning  materials,  by  means  of  which  it  has  been  pos- 
sible to  secure  a better  quality  of  leather  in  much  less  time. 

These  synthetic  tannins  are  prepared  from  rather  expensive 
phenolic  bases.  Incidentally , the  cost  of  the  finished  product 
has  been  comparitively  higher  than  the  natural  tannins.  Because 
of  this  there  has  been  a tendency  among  leather  r anufacturers  to 
avoid  using  them. 

If  it  is  possible  to  produce  a product  which  can  compete  with 
natural  tannins,  it  is  quite  obvious  that  tanners  will  avail  them- 
selves of  the  opportunity.  The  object  then,  is  to  utilize  an  in- 
dustrial waste  product  in  the  manufacture  of  a substitute  for  tan- 
nin. Cymene , a by-product  of  paper  manufacture,  is  the  substance 
used  in  this  work. 


. 


« ■ • .* 


■ 


. 


. 


. 


. 


v’ 


o. 

Historical . 

1 

In  1906,  M.  Hierenstien  produced  from  a condensation  of  py- 
rogallol  and  formaldehyde  a substance,  which  in  water  solution  . 
precipitated  gelatine.  He  obtained  a leather  which  was  more  or 
less  satisfactory,  but  no  attempt  was  made  to  utilize  the  compound 
on  a commercial  basis.  (It  is  to  be  observed  that  both  pyrogallol 
and  formaldehyde  precipitate  gelatin  from  a water  solution  and 
have  tanning  action  on  hide.) 

2 

L.  Meunier  and  A.  Seyewetz  obtained  leathers  by  the  use  of 
an  alkaline  solution  of  hydroquinone ; quinone  behaved  similarly. 

In  both  cases  the  leathers  were  white  in  color,  tough  yet  pliable 
and  without  weight.  The  following  compounds  were  found  to  render 
gelatine  insoluble;-  phenol,  resorcinol,  orcinol,  hydroquinone , 
pyrocatechin,  gallotamiic  acid,  pyrogallol,  p-amincphenol , chlor- 
ophenol,  pioric  acid,  mono-chlorhydroquinone , quinone , and  the 
mono-  and  di sulfonic  acids  of  B-napthol. 

3 

Formaldehyde  tannage  was  produced  by  U.  J.  Thuau  ; but  the 
leather  after  a month  lost  its  firmness,  became  brittle  and  hygro- 
scopic. This  is  probably  due  to  the  oxidation  of  the  formaldehyde 
to  formic  acid.  However,  good  results  were  obtained  in  using 
formaldehyde  as  a preparatory  bath. 

4 

Emil  Fisher  and  X.  Freu&enberg  found  that  on  the  hydrolysis 
of  purified  tannin  ( gal lo tannic  acid)  with  five  percent  sulfuric 
acid,  ninty  percent  of  gallic  acid  and  from  seven  to  eight  percent 
of  dextrose  was  obtained.  From  this  they  concluded  that  tannin 
was  an  ester  of  glucose  with  five  molecules  of  meta  gallic  acid. 

He  prepared  a penta-tricarbomethoxygailoyl  glucose  compound 


. . 

..  . • 


. 


. ; 

. 

. 


. 


• 

. 

. 

. 

* 


4 


which  has  the  following  formula 

p — — o- — 

CHOR-CHOR-CHOR-GH-CHOR-CHgOR 

0 ^OGOOGHg 
where  R»  -C  < >OGQOCHg 

^-OCOOCHg 

This  was  saponified  with  ITaGH,  forming  the  pentagalloyl  glucose. 
This  compound  was  similar  to  tannin  in  every  respect  except  that 
it  was  not  optically  active  as  is  the  natural  tannin.  Due  to  the 
very  difficult  and  complicated  method  of  preparation,  it  is  impos- 
sible to  make  the  tannin  commercially. 

5 

E.  Stiasny  produced  a synthetic  tanning  material  hy  sulfonat- 

ing  crude  cresylic  acid  and  forming  a condensation  product  with 

one  mole  of  formaldehyde  to  two  moles  of  cresylic  acid.  The  excess 

acid  was  neutralized  with  Da OH.  The  soluble  product  obtained  was 

6 

called  Herodol-D,  which  gives  a white,  firm,  and  pliable  leather. 
Like  the  quinone  and  formaldehyde  tannages,  the  leather  lacked 
weight.  The  IJerodol-D  is  recommended  for  use  (1)  as  a preparatory 
hath,  (2)  in  combination  with  natural  tannine,  and  (5)  as  a bleach- 
ing agent. 

After  Stiasny's  work,  there  appeared  quite  a number  of  these 
synthetic  compounds,  which  were  called  Syntans.  All  of  these  are 
condensation  products  of  formaldehyde  and  some  sulfonic  acid,  dif- 
fering in  detail  of  manufacture  and  in  base  of  sulfonic  acid. 

Two  which  differ  from  the  rest  are,  (1)  condensation  products 
obtained  by  heating  phenol  or  eresol  sulfonic  acids  under  mild 

7 

conditions.  Excess  acids  neutralized.  Ho  formaldehyde  is  used, 
and  (2)  condensations  with  formaldehyde,  of  napthalen6  sulfonic 


. • 

. 

. 

. 

. 

5 


8 

acid . 


Theoretical . 


Tanning  consists  of  converting  the  raw,  putrescible  hide  in- 
to a strong,  pliant,  firm,  and  imputrescible  substance,  which 
is  unaffected  to  a degree  by  water.  Any  material  which  will  so 
convert  the  hide  may  be  regarded  as  a tanning  agent. 

The  hide  in  itself  consists  of  an  epidermis,  (the  outer  lay- 
er) and  the  dermis,  which  is  composed  of  two  distinct  parts,  the 
collagen  and  the  corium.  The  collagen  is  very  readily  transformed 
into  gelatins  on  boiling,  whereas  a more  vigorous  boiling  is  neces- 
sary to  convert  the  corium  into  gelatine.  The  corium  forms  the 
fibrillar  structure  noticeable  in  leather.  In  the  preparation  of 
upper  leathers,  the  collagen  is  easily  dissolved  away  due  to  en- 
zyme action;  the  corium  is  also  affected,  but  not  dissolved. 

9 

L.  Msunier  concludes  that  tanning  consists  of  the  following 
phenomena  occur in?  simultaneously : - 

I.  Chemical  Action 

It  is  generally  accepted  that  the  hide  substance  is  of 
a protein  nature,  and  has  somewhere  in  its  molecular  structure  an 
amino  group.  Whether  it  is  a primary  or  secondary  amino  group 
is  not  definitely  known.  Usually  the  simplest  formula  to  desig- 
nate hide  substance  is  R-NHo . Another  formula,  with  a secondary 
amino  group  is:- 


NK 

/ 

R 


. 

. 


?his  is  supposed  to  interact  with  water  to  give:- 

m 


/ 


R 


\ 


f H*° 


HEoR-COOE 


G-0 


6. 


10 

Ileunier  and  Seyewetz  demonstrated  that  aqueous  solutions  of 
pure  phenols  do  not  render  gelatine  insoluble,  but  that  their  oxi 
dation  products  do. 


R-IIHg  -f  2C..H402  > R-N(C6H402)  4 CgE4(0H)2 

or 

2R-LTHg  + 3C6H402  > 2C6R4(0H)2  4 C6H402(  E-il ) 2 

With  formaldehyde  the  following  reaction  apparently  occurs :- 
2R-EE2  4 C-S20  > R-1?=CH2  4 EgO 

The  resulting  compounds  are  of  a colloidal  nature  and  compar- 
atively stable. 

II.  Adsorption 

By  the  action  of  the  gel  constituting  the  swollen  hide 
fibres,  the  colloidal  tannin  is  precipitated  on  the  surface  of  the 
fibres.  This  results  in  a concentration  of  the  tannin  solution 
around  the  fibres,  which  aids  in  adsorption. 

III.  Transformation 

A part  of  the  precipitated  tannin  is  transformed  from 
the  reversible  to  the  irreversible  , insoluble  form  by  the  action 
of  oxidation,  hydration  and  polymerization.  This  transformed  tan- 
nin is  called  "Bloom”. 

IV.  Osmotic  Phenomenon. 

Due  to  the  action  of  adsorption,  transformation  and 
chemical  reaction,  tannins  are  precipitated  on  the  corium  fibres. 
As  result,  osmosis  occurs  and  the  hide  fibres  are  dehydrated, 
leaving  an  increasingly  marked  formation  of  fibrilliar  structure. 


' i ' 


* 


- 


- • 

, 

* 

. 

. 

* 

Tannins  which  show  all  four  phenomena  may  he  classed  as  true 
tannins,  while  those  that  do  not,  as  Alum  tannage,  e.g.,  may  he 
considered  as  pseudo-tannins. 

Experimental. 

Preparation  of  Gyrnene  Sulfonic  Acid. 

The  cymene  received  was  in  an  impure  state,  having  about  fif- 
ty percent  of  water  and  other  impurities  with  it.  On  standing, 
the  water  separated  into  a distinct  layer  and  was  removed  by  means 
of  a separatory  funnel.  The  pure  cymene  was  distilled  off  at  174- 
178 'C,  and  after  further  distillation  was  dried  with  anhydrous 
calcium  'chloride. 

One  hundred  cc.  of  cymene  was  slowly  added  to  an  equal  volume 
of  concentrated  sulfuric  acid,  Sp.  Gr.  1.84,  which  had  been  heated 
to  100 *C.  The  cymene  was  easily  sulfonate!,  with  a liberation  of 
heat,  it  was  necessary  to  keep  the  temperature  constant  at  1G0#C, 
because  of  the  ease  with  which  a too  vigorous  reaction  resulted, 
forming  a highly  condensed  and  insoluble  black  substance.  Since 
the  reaction  is  an  exothermic  one,  no  heating  is  necessary  after 
it  has  been  once  started. 

The  excess  acid  was  neutralized  with  ten  percent  ilaOH,  which 
was  added  at  such  a rate  as  to  keep  the  temperature  below  100° C. 
After  neutralization  the  mixture  of  cymene  sulfonic  acid  and  sod- 
ium sulfate,  was  heated  on  the  water  bath  for  several  hours  until 
a reddish  brcwg.,  clear  solution  was  obtained. 

The  reaction  between  cymene  and  sulfuric  acid  is:- 


. 

' 


. ■ A ■ > 


- 


. 


■ 


. ' 


8 


H GH 


CH* 


<0 


1/ 

\ 


3 


+ H2S04 


CH^<C 


H CH3 

1/  ' 
C 


GH3 


CH<7 


sogH 


Tests. 

On  addition  of  a few  drops  of  the  sulfonic  acid  solution  to 
two  cc.  of  a one  percent  solution  of  gelatine,  a finely  divided 
white  precipitate  was  brought  down.  It  was  insoluble  in  dilute 
acid,  but  soluble  in  concentrated  acid,  giving  a rather  colloidal 
solution.  The  precipitate  dissolved  in  dilute  IJaOH  giving  a clear 
solution.  Boiling,  the  precipitate  gave  a colloidal  solution. 

The  sulfonic  acid  solution  gave  similar  results  with  aniline  hy- 
drochloride. Ho  reaction  was  obtained  with  ferric  chloride. 

Tanning  Action. 

The  sulfonic  acid  solution  obtained  was  diluted  to  five  litres 
A piece  of  unhaired  calf  skin  was  immersed  in  it  and  after  two 
days,  the  product  was  removed,  washed,  lightly  oiled  and  dried. 

The  result  v/as  a white,  pliable  and  strong  leather  with  a distinct 
fibrillar  structure.  The  leather  was  destroyed  on  boiling  and  was 
almost  completely  detanned  on  soaking  in  water  for  0116  week.  In 
that  respect,  the  leather  was  similar  to  an  alum  tannage. 

A second  piece  of  calf  skin  was  soaked  in  the  sulfonic  acid 
solution  for  one  day  and  then  placed  in  an  oak  bark  solution  of 
approximately  four  percent  tannin  content.  At  the  end  of  five 
days,  a leather  was  produced  which  v/as  similar  to  ordinary  oak 
bark  leather  except  that  the  grain  v/as  finer  and  the  color  lighter. 

Condensation  of  Cymene  Sulfonic  Acid  with  Formaldehyde. 

To  one  hundred  oc.  of  tv/enty  percent  fuming  sulfuric  acid  v/as 
slowly  added  an  equal  volume  of  cymene.  The  sulfonation  took  place 


. 


. 


. 


, 

' 

. . 


9 


very  easily,  the  highest  temperature  necessary  being  60*0.  With 
the  fuming  sulfuric  acid  charring  does  not  occur  so  readily  as 
with  the  concentrated  sulfuric  acid. 

The  sulfonic  acid  solution  was  then  cooled  to  room  tempera- 
ture and  formaldehyde,  ratio  of  one  mole  formaldehyde  to  two  moles 
cyrnene,  was  then  added  slowly  with  vigorous  stirring.  The  temper- 
ature was  not  allowed  to  ascend  above  35*0  as  highly  condensed, 
water  insoluble  products  may  form.  The  clear  reddish  sulfonic 
acid  solution  became  dark  in  color  and  rather  viscous.  After  con- 
densation, the  excess  acid  was  neutralised  with  ten  percent  UaOH. 
Care  was  taken  that  the  temperature  was  kept  below  35°  during  neu- 
tralisation. The  odor  of  formaldehyde  disappeared  completely. 
After  having  the  product  slightly  basic,  it  was  heated  on  the  water 
bath  to  insure  maximum  solution  of  the  condensation  compound.  The 
solution  was  of  a semi-colloidal  nature. 

Tests. 

With  a one  percent  gelatine  solution,  a white  precipitate 
was  obtained  which  on  standing  turned  green.  It  y/as  soluble  in 
NaOH,  giving  a clear  solution.  Insoluble  in  dilute  and  concentra- 
ted acids.  Boiling  with  concentrated  acid  produced  a colloidal 
solution.  Similar  results  were  obtained  with  aniline  hydrochlor- 
ide . 

Tanning  Action. 

With  the  condensation  product  alone,  a cream  colored,  plia- 
ble and  firm  leather  was  obtained,  after  two  days.  Boiling  in  wa- 
ter destroyed  the  leather,  but  not  as  easily  as  the  cyrnene  sulfon- 
ic acid  leather.  On  soaking  in  water  for  one  week,  it  lost  con- 
siderable weight,  but  still  was  leather. 


- 


, 


. 


- : 


* 


l 


10. 

A leather  similar  to  the  one  produced  by  the  combination  of 
cymene  sulfonic  acid  and  oak  bark  solution,  was  obtained  with  a 
one  day  soaking  in  the  condensation  product  and  subsequent  tan- 
ning in  oak  bark  for  five  days. 

By  making  a mixture  of  the  condensation  substance  and  oak 
bark,  a leather  was  produced  in  five  days.  It  was  lighter  in 
weight,  of  a finer  texture  and  very  soft  and  pliable,  with 
strength.  This  leather  resisted  boiling  as  did  the  other  combin- 
ation tannages. 

Other  Substances. 

The  sulfonic  acids  of  benzene,  toluene  and  zylene  were  pre- 
pared and  found  to  precipitate  gelatine  from  solution.  All  of 
the  precipitates  were  soluble  in  dilute  ITaOH  and  concentrated 
acid  and  insoluble  in  dilute  acid.  Similar  results  were  obtained 
with  aniline  hydrochloride  instead  of  gelatine.  Hone  of  the  solu- 
tions had  any  tanning  action. 

An  attempt  was  made  to  utilize  furfuraldehyde  by  a similar 
process,  but  the  compound  could  not  be  sulfonated. 

Summary  and  Conclusion. 

It  has  been  found  that  the  sulfonic  acid  of  cymene  has  a def- 
inite tanning  action  similar  to  that  of  alum  tannage.  The  con- 
densation product  also  produces  a similar  leather,  but  of  a more 
resistant  character. 

Either  the  condensation  product  or  the  sulfonic  acid  can  be 
used  as  (1)  a preparatory  bath,  (2)  in  combination  with  natural 
tannins,  and  (3)  as  a bleaching  agent.  The  sulfonic  acid  conden- 
sation product  produces  a better  product  for  all  three  purposes. 

Just  what  occurs  when  formaldehyde  is  added  to  the  sulfonic 


' 

- 

. C 

. 


. 


11. 

acid  is  not  known,  inasmuch  as  the  product  formed  is  of  a col- 
loidal nature. 


Bibliography. 


(1). 

Collegium 

Bo.  236,  454,  (1906) 

• 

(2). 

Compt.  Rend. 

146,  987-989,  (1908) 

• 

(3). 

le  Cuir 

Nos.  8 & 9,  201-208, 

(1909)  (2). 

(4). 

Ber . 

45,  915-935,  (1912). 

(5). 

<-1  • ii  • J-i  • • jSl  • 

8,  208-211,  (1913). 

(6). 

Austrian  Pat 

. 58,  415. 

(7). 

British  Pat. 

2^,  21o . J . A . ' . 0 . ii . 

9,  201,  (1914) 

(Q). 

British  Pat. 

• 

<A 

• 

o 

. 

. 

00 
CO 
1 — 1 

9,  447,  (1914) 

(9). 

Chemie  et  Ind.  1_,  71-80,  272-276, 

(1918). 

(10). 

Collegium 

(1908),  pp.  195. 

